A system may include electrically operated devices for performing tasks and/or providing enjoyment to a user. For example, a system may comprise, but is not limited to including motors, solenoids, radio receivers, display devices, computers, and cooking appliances. Electrically operated devices in the system may be powered via an electrical energy storage device such as a battery or capacitor when the system is remote or untethered from a stationary power grid. The electrical energy storage device may be adequate for operating the electrically operated devices for a limited amount of time or charge consumption, but the electrical energy storage devices have limited capacity. Consequently, the electrical energy storage device may be periodically returned to the stationary power grid for recharging. Further, the system may be designed to operate with lower charge density energy storage devices (e.g., lead-acid batteries), thereby, potentially increasing the frequency of system charging. Therefore, it may be desirable to increase operating time of a system that is electrically powered via an electrical energy storage device so that less frequent energy storage device charging may be necessary.
The inventors herein have recognized the above-mentioned issue and have developed an add-on battery system, comprising: a battery; a bi-directional DC/DC converter; and a controller including instructions stored in non-transitory or non-volatile memory to direct current flow into the battery and out of the battery via the bi-directional DC/DC converter in response to conditions of an external electrical energy storage device.
By controlling current flow into and out of a battery of an add-on battery system in response to conditions of an external electrical energy storage device via a bi-directional DC/DC converter, it may be possible to extend operating time of the external electrical energy storage device and the external system in which it operates. Further, electrical charge stored in the add-on battery system may be applied to the external system more efficiently. For example, charge from the add-on battery system may only be delivered during some conditions in response to an electrical load being applied to the external electrical energy storage device. In particular, the add-on battery system may only supply electrical power (e.g., current and voltage) when the external electrical energy storage device has a state of charge greater than a threshold and when the external load is consuming power from the external electrical energy storage device. Consequently, the add-on battery system supplies electrical power during conditions when it may be most efficient. Use of add-on battery power may be more efficient when a load is being supplied to the external electrical energy storage device because more electrical power may be applied to the electrical load rather than to less efficient charging of the external electrical energy storage device. Additionally, the bi-directional DC/DC converter allows the add-on battery system to be charged via a charger that charges the external system battery.
The present description may provide several advantages. In particular, the approach may improve efficiency of electrical power transfer from one electrical system to another. In addition, the approach may also provide energy transfer between systems without having to provide large cables between electrical systems. Further, the add-on battery system may be electrically coupled to an external system at any time without having to deactivate the external system. Further still, the add-on battery system may interfere less with fuel gauge displays of the external system.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.